Construction\nof Six-Membered Lactam and Lactone Structures\nvia Ligand-Free Pd-Catalyzed C–H Activation/[5 + 1] Cyclization\nCarbonylation

An approach for the ligand-free Pd-catalyzed C–H\nactivation/[5\n+ 1] cyclization carbonylation by employing readily available ClCF<sub>2</sub>COONa as a carbonyl source via difluorocarbene transfer and\nhydrolysis has been developed. The current protocol enables us to\nobtain a series of carbonylation cyclization product benzopyranone\nand phenanthridinone derivatives in up to 91% yield with excellent\nfunctional group compatibility. This protocol has the advantages of\nmild reaction conditions, wide applicable substrates, and simple and\nsafe operation and provides a new method for the synthesis of complex\nlactam and lactone compounds.